1. Field of the Invention
This invention relates to a graphite intercalation compound and a production method thereof.
2. Description of the Related Art
The graphite intercalation compound is produced by intercalated a different kind of substance in a space of graphite or the like having a layer structure, is capable of improving electric conductivity and is applicable to functional material such as a catalyst utilizing properties of the intercalated substance. Various intercalation compounds are synthesized and their physical properties and/or applications thereof are studied.
As examples of a different kind of substance intercalated in a space of graphite having a layer structure, alkali metals such as Li, Na, or K, alkaline-earth metals such as Ca, Sr, or Ba, rare earth elements such as Sm, Eu, or Yb, transition metals such as Mn, Fe, Ni, Co, Zn, or Mo, halogens such as Br.sub.2, ICl, or IBr, acids such as HNO.sub.3, H.sub.2 SO.sub.4, HF, or HBF.sub.4, and compounds such as MgCl.sub.2, FeCl.sub.2, FeCl.sub.3, NiCl.sub.2, AlCl.sub.3, or SbCl.sub.5 are reported.
Conventionally, the graphite intercalation compound intercalated a different kind of substance in a space having a layer structure is produced by (a) a method of contacting graphite with a gaseous phase or a liquid phase of substance to intercalate, or (b) an electrolysis of electrolyte including intercalated substance using a graphite electrode. For example, a graphite intercalation compound using alkali metals is obtained by coexisting graphite with the alkali metals under a vacuum and heating them. A graphite intercalation compound using halogens is produced by contacting graphite with a liquid phase or vapor of Br.sub.2, ICl, or IBr. A graphite intercalation compound using alkaline-earth metals such as Ca, Sr, or Ba, or rare earth elements such as Sm, Eu, or Yb is produced by mixing graphite ultrafine powder with metal powder, applying pressure to 1 to 2 MPa, and pressureless sintered.
A graphite intercalation compound using transition metals such as Fe, Co, or Mo is produced by synthesizing an intercalation compound using a chloride of these metals, and reducing the compound slowly at/or below room temperature using NaBH.sub.4, LiAlH.sub.4, Na or the like. The reduction method has, however, low reproducibility and a drawback that a graphite intercalation compound of transition metals cannot be stably obtained.
Above-mentioned conventional methods for producing a graphite intercalation compound utilizes powder calcination, powder-gaseous/liquid phase reaction, electrolysis or the like. These normal production methods are suitable for obtaining a graphite intercalation compound as an aggregate. However, a graphite intercalation compound in a controlled shape, distribution and/or states, for example, producing an intercalation compound on a specified nanoscase area of graphite, cannot be produced.
As described above, conventional graphite intercalation compound has drawbacks of low reproducibility in intercalating transition metals in a space of graphite having a layer structure, and of limited number of applicable transition metals.
Conventional methods for producing a graphite intercalation compound are suitable for obtaining a graphite intercalation compound as an aggregate. However, a graphite intercalation compound cannot be produced in a controlled shape, distribution and/or states. To enlarge a range of graphite intercalation compound applications, it is needed that a graphite intercalation compound can be produced in a controlled status, i.e. selectively producing an intercalation compound on a specified nanoscase area of graphite.